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Millennial-scale change on a Caribbean reef system that experiences hypoxia

Citation

Figuerola, Blanca et al. (2021), Millennial-scale change on a Caribbean reef system that experiences hypoxia, Dryad, Dataset, https://doi.org/10.5061/dryad.zs7h44j8s

Abstract

Coastal hypoxia has become an increasingly acknowledged threat to coral reefs that is potentially intensifying because of increased input of anthropogenic nutrients. Almirante Bay (Caribbean Panama) is a semi-enclosed system that experiences hypoxia in deeper waters which occasionally expand into shallow coral reefs, suffocating most aerobic benthic life. To explore the long-term history of reefs in the bay we extracted reef matrix cores from two reefs that today experience contrasting patterns of oxygenation. We constructed a 1800-year-long record of gastropod assemblages and isotope compositions from six U-Th chronologically-constrained reef matrix cores. We extracted two cores from each reef at 3 m water depth and two additional cores from a deeper part (4.8 m) of the hypoxia-exposed reef. Results show that the deeper part of the hypoxic reef slowed in growth and stopped accreting approximately 1500 years BP while the shallow part of the reef continued to accrete to the present day, in agreement with a model of expanding hypoxia at this time. Our proxy-based approach suggests that the patterns of increasing herbivores and decreasing carbon isotope values in the deeper part of the hypoxic reef may have been driven by an increase in hypoxia via eutrophication caused by either natural changes or human impacts. Similar patterns in these paleoindicators occurred in the shallow part of the hypoxic reef during the last few decades. This suggests that hypoxia may be expanding to depths as shallow as 3 m and that shallow reefs are experiencing greater risk due to increased human activity.

Funding

SENACYT, Award: 47-2017-4-FID16-239

Smithsonian Institution

Smithsonian Tropical Research Institute

Texas A and M University

H2020 Marie Skłodowska-Curie Actions, Award: 801370

Secretary of Universities and Research (Government of Catalonia; Beatriu de Pinós-Incorporació)*, Award: 2019-BP-00183

Ministerio de Ciencia e Innovación, Award: JCI-2017-31478

SENACYT, Award: 47-2017-4-FID16-239